With more Americans eating out, at least three times a week, and a lack of adequate nutritional information available to consumers, University of Hawai‘i at Mānoa geobiology professor A. Hope Jahren and postdoctoral researcher Brian A. Schubert wanted to examine the oil content in a growing trend on American restaurant menus: french fries. What they found was that the majority of national chain restaurants on O‘ahu served fries containing corn oil—which is higher in cholesterol-raising saturated fat than other vegetable oils such as canola, soy and safflower—as compared to small mom-and-pop restaurants.

The team found that the majority (69 percent) of the national chain restaurants served fries containing corn oil, whereas this was true for only a minority (20 percent) of the small businesses. Jahren and Schubert concluded that fries at the mom-&-pop restaurants are slightly healthier than at the big chains, thus making them a better dining choice.

Jahren and Schubert conducted their research over a year and a half by purchasing fries at 134 restaurants on the island of O‘ahu and analyzing the expressed oil for carbon isotope value. Because O‘ahu is geographically small, Jahren and Schubert were able to sample 68 of the 101 national chain fast food restaurants on the island, as well as a similar number of small local restaurants. Thus, they captured a profile of fast-food fries available to a population. Local restaurants sampled include Big City Diner, Rainbow’s Drive Inn, Like Like Drive Inn, Kanpai Bar and Grill and South Shore Grill.

“Surprisingly, there was such a clear difference between the amount of corn oil in fast-food chains and the local mom-and-pop restaurants,” said Jahren. “Since corn oil is more expensive than other vegetable oils, we hypothesized that it would be a simple function of what was cheapest.”

However, Jahren and her team discovered that to make corn oil cost-effective, it is necessary to contract ingredients on a large scale from preferred distributors, which makes sense for national chains, but not from a small business profit perspective.

Fast-food restaurants are not providing enough ingredient and nutrient content at the point of purchase. “People want to eat right, they just don’t know how,” noted Jahren. “Multiple studies have demonstrated that knowledge of ingredients leads to changed eating habits.”